The present invention relates to optical bar code scanning systems and more particularly to a portable bar code scanning device which can be used in either a portable mode of operation or in a stationary mode of operation.
In present-day merchandising point-of-sale operations, data pertaining to the purchase of a merchandise item is obtained by reading data encoded indicia such as a bar code label printed on or attached to the merchandise item. In order to standardize the bar codes used in various point-of-sales checkout systems, the grocery industry has adopted a uniform product code (UPC) which is in the form of a bar code. Reading systems which have been constructed to read this type of bar code include hand-held wands which are moved across the bar code, and stationary optical scanning systems normally located within the cabinet structure of a checkout counter, in which the bar code is read when a purchased merchandise item is moved across a window constituting the scanning area of the counter, which movement is part of the process of loading the item into a baggage cart. Hand-held wands or scanners emit a single scan line which is directed over the bar code by the operator while the stationary optical reader systems emit a multiline scan pattern through which the bar code label is moved, enabling a higher throughput of scanning bar code labels to occur over that of the hand-held scanner. Where the merchandise consists of soft materials such as clothing or other type of wearing apparel, hand-held scanners have been employed to read the bar code labels attached to the material in which the bar code label is manually positioned adjacent the hand held scanner. It has been found that this type of scanning operation has been ineffective in many cases because the bar code label was not positioned within the depth of field of the scanner or that the projected scanning pattern was not properly positioned adjacent the bar code label. In order to overcome this problem, portable scanning devices have been developed which allow hands free scanning operations to occur enabling the operator to use both hands in moving the merchandise item across the scanning device. One example of this type of scanning device is the above cited co-pending application Ser. No. 07/625,331 in which the portable hand-held scanner is positioned on a portable scanning device which utilizes the scanning light beams from the operating hand-held scanner to project a scan pattern on a scanning window in the scanning device. Where the checkout operation requires the hand-held scanner to be used in a hand-held mode, the scanner is removed from the scanning device. To enhance the performance of the scanning operation, it would be desirable for the electronics associated with the operation of the hand-held scanner to know what scanning mode the scanner is in so as to initiate an operation of the scanner or to alter scanner parameters which affect the operating performance of the scanner. For example, the scanner's trigger mode can be changed from a finger-pull trigger to an automatic-read operation when a hands-free scanning operation is desired. Another parameter is the level of intensity of the scanning light beams with the level increasing when the scanning device is used in the hand-held mode.
The background art known to the applicants at the time of the filing of this application includes U.S. Pat. No. 4,369,361 which discloses a portable stand-alone desk-top laser scanning workstation including a laser scanning head mounted above a support base facing the operator in which objects bearing bar code symbols to be scanned are passed under the head, and U.S. Pat. No. 4,766,297 which discloses a support member for supporting a portable hand-held scanning device in which the support member includes structure for sensing the presence of an object between the head portion and the base portion of the support member and for automatically initiating a reading of a bar code symbol by the portable handheld scanning device each time the sensing structure senses the presence of an object.